50 Hz vs. 60 Hz

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jkim780

Senior Member
What would be the advantage or disadvantage of one system over another?

What would happen if you use 60hz rated equipment (motors, appliances, devices, etc)to 50hz system or vice versa?
 

jbwhite

Senior Member
Re: 50 Hz vs. 60 Hz

the advantage is not as important an issue as what your utility provides. You have little choice in the matter.

motors etc will work fine but run a bit faster or slower. clock will be off time.
 

c-h

Member
Re: 50 Hz vs. 60 Hz

Lots of stuff is dual frequency now. It is all history. There is no given advantage to either frequency for most applications.

For some things there are: 60 Hz transformers are smaller, 60 Hz motors spin faster and you can settle with a smaller motor. That's often good because it saves money so why not 400 Hz?

The bad part is that motors and generators that spin faster subject the parts to larger forces. While probably unimportant for a gas turbine of a few MW, I think it will be very important if you design a 1000 MW nuclear reactor.

When electricty generation began in the 19th century manufacturing technology was much less developed. You didn't have to go to very large generators and motors before the speed became a mechanical problem. This contributed to the preference for low frequency AC (16 2/3 Hz and 25 Hz) for some applications with large motors.

Look at the engine in a motorbike, car and truck respectively: As the size goes up, the rpm goes down. The huge engines of a supertanker do less than 100 rpm.
 

dave_asdf

Member
Location
tampa florida
Re: 50 Hz vs. 60 Hz

the first generator was a 60 hz generator. it was based on 'ideal frequency' which tesla calculated at about 60 when he and westinghouse built the first AC generator on Niagara falls. tesla came up with the ideal frequency based on resonance and permittivity. i don't quite understand it but i can't imagine a 150 kva transformer operating at 10 GHz or .1 Hz. these are obviously extremes but, that's how i think of it. the rest of the world uses 50 Hz because the math is easier.

the ideal frequency is actually 58.7 i think
 

wyatt

Senior Member
Re: 50 Hz vs. 60 Hz

not that it really applies here. but most aircraft use 115v 400hz there must be some advantage.
 

jbwhite

Senior Member
Re: 50 Hz vs. 60 Hz

Originally posted by wyatt:
not that it really applies here. but most aircraft use 115v 400hz there must be some advantage.
Not that this applies either, but those 60 hz to 400 hz gen sets make a very annoying high pitch noise. I hate having to work arround them.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Re: 50 Hz vs. 60 Hz

Aircraft use 400Hz largely because the filters to get DC are smaller and lighter.

Steve
 

dereckbc

Moderator
Staff member
Location
Plano, TX
Re: 50 Hz vs. 60 Hz

Originally posted by wyatt:
not that it really applies here. but most aircraft use 115v 400hz there must be some advantage.
Actually it is very relevant to the question being asked. So here is the answer. The lower in frequency you go, the larger (physical size/weight) the transformers and generators are. The flip side is the higher in frequency you go the more voltage drop you have. 50 and 60 Hz is a good medium between size and voltage loss on a system. For example take 20 Hz. It would be great in terms of voltage drop, almost down to I*R, but the size of the transformer for you house would be the size of you car.

So for aircraft and boats 400 Hz is chosen because a tremendous amount of weight and space savings are gained while the area is small enough the voltage drop does not pose a real problem.

I more tidbit, DC Switch Mode Power Supplies. Before they became available the way DC power was converted was to take line voltage to a transformer at 60 Hz and step it down/up to a usable voltage, rectify it to DC, and filter. This is known a linear DC power supply.

Switch Mode is different. You take line voltage and rectify immediately. Then invert the DC back to an AC signal of say 40, 50, or up to 100 KHz, then run it through a transformer to step the voltage up or down, rectify and filter again at the desired DC voltage. What makes this appealing? Very simple you do not need a large, expensive, and heavy 50-lb @ 60 Hz transformer on the input. You just need a very small, light, and inexpensive 2-lb transformer operating at high frequencies.

[ December 23, 2005, 01:45 PM: Message edited by: dereckbc ]
 

beanland

Senior Member
Location
Vancouver, WA
Re: 50 Hz vs. 60 Hz

Another issue to remember was the effect of visual flicker. 50Hz has more noticable flicker than 60Hz.

Also, reasonable distance for power transport is inverse to frequency. 400Hz works for small distances like a ship or airplane. 133Hz was used at early hydroelectric and mine sites. 25Hz works well for slow steam-piston powered devices. Lots of compromises. Obviously, 50Hz and 60Hz are reasonable choices and Tesla won in USA. Old Los Angeles area power was 50Hz!
 
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